Hard Cargo Case for Roof Rack/basket

Hey folks

Any of you with a roof rack with basket that have a hard case for storing items you'd recommend? I'd like to keep it 8-12 inches tall at most because I don't need any MORE wind resistance than I have already... I seem to find all of the ways to ignore the laws of aerodynamics with my Jeep as it is already. Basket is about 50" by 58" and about 6-8" deep. I'm looking for something to put general camping supplies in. I'd just throw things in the basket but it has to handle getting hit with tree branches I inevitably have to drive through when 4x4 camping.

Things I've looked into

Pelican is HUGELY expensive like $400 to START

Hardigg military surplus on ebay is more reasonable but I can't find one short enough save the medical cases that are still 13" and that is what I'm leaning towards.

I've been looking at musical keyboard cases and rifle/rocket launcher case surplus as an alternative.... but at this point when I start looking at rocket launcher cases... I can't help but feel I've over complicated things a *bit* ... still it has a certain ring to it. =)

Some of the mini van style ones for Thule and Yakima well yeah mini van...